In the gas processing industry, excess sample fluid, often referred to as “boil off gas” or “BOG”, is disposed of by flaring or other disposal means. When provisions are made to avoid flaring, such as by recirculating excess extracted sample to the take-off source or pipeline, sample take-off and return of unused take-off fluids are typically carried out by using a first take-off probe and a second return probe. The addition of a discrete pathway and the second return probe for reinjection, particularly in the case of a highly expandable and even explosive fluid such as natural gas, adds additional requirements for system equipment, installation, and maintenance. The use of such additional equipment also presents further opportunities for leakage and/or system failure. Moreover, in cases of cryogenic fluid sampling, such as Liquid Natural Gas (LNG), conventional design requires the sample extraction probe to be located close to the sample vaporizer and conditioner so as to avoid issues resulting from pre-vaporization and deadheading.
A system that allows for reinjection of unused take-off fluids into the pipeline source without the need for additional equipment, installation, and/or maintenance requirements to the system, such as requirements associated with having a discrete fluid pathway through a second return probe, would be useful in overcoming traditional problems associated with conventional system designs in the gas processing industry, for example, avoiding leakage and/or system failures that result from the use of unnecessary system components.